Various magnetic recording systems such as hard disk drives utilize a write head to record data on a magnetic medium. Data to be recorded is provided to the write head coil as an alternating electrical current. The electrical current passes through a metallic coil wrapping around the write head, generating a magnetic field. The magnetization state of a pole tip in the write head is switched by the magnetic field. As the magnetized pole tip is passed over the magnetic storage medium, for example a spinning ferromagnetic platter, the magnetization of regions of the magnetic medium below the pole tip are altered and can later be read back to retrieve the data.
The write (recording) process is challenging at high speeds in magnetic recording. Conventional write current waveforms used to drive the write head to record data on a given track are fixed in terms of the write current pulse characteristics. However, the switching response of the magnetic system is not linear. The magnetic response for one write pulse can be considered as a three-stage process: switching (stage I), transition to saturation (stage II), and saturation (stage III). The third and even possibly the second stage may be truncated in the case of a high density recorded pattern when the bit cell period (T) is less than the magnetic switching time. The non-linearity between excitation and response signals is more pronounced as the data rate increases and the bit sequence includes more high frequency transitions. The following negative effects accompany this recording process: first, an increase in the curvature of the transitions; second, a bit-to-bit transition degradation; third, a track width modulation. As a result, the global recording performance degrades, and data rate and areal density are limited.
Because magnetic recording systems are continually being enhanced with areal density and faster data rates, there exists a need in the art for improving the write process.